Wisconsin Kirtland's Warbler Update

July 16, 2013

Adams County

Nest monitor Valarie Michel plays a recorded song to attract a Kirtland's warbler with missing bands, so that the bird can be identified.

Preliminary results of the 2013 breeding season indicate
that 9 pairs of Kirtland’s warblers made 12 nesting
attempts at the Adams County sites. At least 4 nests
fledged 13 young. Eight nests failed, most likely due to
predation, including two nests that had been parasitized by
brown-headed cowbirds. Because we did not approach
nests, the total number of parasitized nests is not known.
All of the successful nests, however, fledged Kirtland’s
warbler offspring and no cowbird young.

We received special help with identifying a male from
Frank Boll, award winning videographer now retired from
Wisconsin Public Television. A previously banded male
had lost a color band from each leg, which prevented us from identifying him with certainty. The banding crew
attempted to recapture this bird in May in order to read the number on its aluminum band, but the capture was not
successful.

Frank Boll uses a Swarovski spotting scope to read tiny numbers on an aluminum leg band of a male Kirtland’s warbler.

Frank, who was filming migratory songbirds for Sumner Matteson of the DNR, offered to use a
high-powered Swarovski spotting scope used in filming to read the band numbers from a
distance. Nest monitor Valarie Michel escorted Frank to the bird’s territory on June 12 and
used a playback recording of a male Kirtland’s warbler song to draw the male in close. Although Frank could not see all the numbers, he was able to report combinations of numbers
and their positions on the band. After comparing Frank’s numbers to our banding and nest
monitoring records, we are fairly confident that this male was banded in 2008, our first year of
banding at the Adams site. This bird returned to Adams County in 2009 and 2010, was most
likely a bird found in 2011 with one band missing from the left leg, and probably the same bird
found last year with a band missing from each leg. Many thanks to Frank for sharing his time
and skills with optical equipment to document the male.

Singing male in Marinette County

Photo by Jack Swelstad

Marinette County

Jack Swelstad, a volunteer surveyor, and Daryl
Christensen, nest monitor, took turns visiting the
territory of a 4-yr-old male in Marinette County. A
female was observed leaving a nest with 3 eggs on
June 17. Unfortunately, the nest was found empty
on June 26, too soon for young to have fledged. It
is uncertain whether a second nesting attempt was
made. Adults, however, were no longer present at
the site on July 13, making it unlikely that nesting
was successful for this pair.

Statewide Surveys

Very few reports were made of birds outside of Adams County this year. Jack Swelstad found
two males in Marinette County: one male banded in 2011 was found on his same territory for
the third consecutive season (see nesting report above); a second unbanded male was located
about 10 miles from the banded bird.

DNR biologist, Steve LaValley, kept up his record of annually reporting a Kirtland’s warbler.
This one was unbanded in Douglas County at a site where folks from UW –Superior also heard
a male singing on a different day according to Steve.

Only one unconfirmed report was made this year and it was from Bayfield County.

Adams County fledgling perches next to a pine cone on a jack pine branch.

Photo by Daryl Christensen

Banding

Ron Refsnider and a banding crew consisting of Joel
Trick, Daryl Christensen, Kelly Vanbeek of
USFWS, and Jack Swelstad, successfully captured
and banded the second Marinette County male on
June 11.
Hoping to band the Douglas County bird, Ron tried
to re-locate it on June 22 with no luck. Interestingly,
two males were heard singing in a new area in
Adams County on June 20. One of the birds, still
singing in the new area on June 24, was determined
to be unbanded and thus a new bird at the site. The
other bird was never identified. Given last year’s
occurrence of a bird from Bayfield showing up late
in June at the Adams site, it is possible that this male
was actually the missing Douglas bird. It was not
captured or banded.
Ron, Joel, and the nest monitors are attempting to
capture and band fledglings at the Adams site this
week. We hope that this effort will allow us to document
fledglings returning to Adams County next
year.

Cowbird Trapping

Cowbird traps were removed shortly after July 1 following 11 weeks of trapping. Barry Benson
of APHIS Wildlife Services, Inc. will submit final tallies later this month.